Hydrogenation unsaturated hydrocarbons

Many of the significant reactions of unsaturated hydrocarbons (hydrogenation, isomerization, carbonylation, oxidation, polymerization) are catalyzed heterogeneously by metals in or near Group VIII or homogeneously by salts and complexes of these elements. Those reactions effected in both systems are discussed in terms of probable common intermediates anomalies, where they occur, are ascribed either to the ability of surfaces to form intermediate species which cannot be stabilized by single metal atoms or to the ability of the latter to coordinate simultaneously more than one hydrocarbon molecule. 

Stereochemistry, of unsaturated hydrocarbon hydrogenation, 16, 123 Structure, of cracking catalysts, 4, 87 Surface area measurements, for studying contact catalysts, 1, 66 Surface barrier effects, in adsorption, 7, 269... 

Cold concentrated sulphuric acid will remove unsaturated hydrocarbons present in saturated hydrocarbons, or alcohols and ethers present in alkyl halides. In the former case soluble sulphonated products are formed, whilst in the latter case alkyl hydrogen sulphates or addition complexes, that are soluble in the concentrated acid, are produced. 

Unsaturated hydrocarbons dissolve through the formation of soluble alkyl hydrogen sulphate ... 

The chemistry of propylene is characterized both by the double bond and by the aHyUc hydrogen atoms. Propylene is the smallest stable unsaturated hydrocarbon molecule that exhibits low order symmetry, ie, only reflection along the main plane. This loss of symmetry, which implies the possibiUty of different types of chemical reactions, is also responsible for the existence of the propylene dipole moment of 0.35 D. Carbon atoms 1 and 2 have trigonal planar geometry identical to that of ethylene. Generally, these carbons are not free to rotate, because of the double bond. Carbon atom 3 is tetrahedral, like methane, and is free to rotate. The hydrogen atoms attached to this carbon are aUyflc. 

Carbon, hydrogen and possibly oxygen Resin and derivatives Natural drying oils Cellulose derivatives Alkyd resins Epoxy resins (uncured) Phenol-formaldehyde resins Polystyrene Acrylic resins Natural and synthetic rubbers Carbon monoxide Aldehydes (particularly formaldehyde, acrolein and unsaturated aldehydes) Carboxylic acids Phenols Unsaturated hydrocarbons Monomers, e.g. from polystyrene and acrylic resins... 

The earbon-to-hydrogen bond is always a single bond. While the resulting bond between earbon and hydrogen is always a single bond, earbon does have the capability to form double and triple bonds between itself and other carbon atoms, and/or any other atom that has the ability to form more than one bond. When a hydrocarbon contains only single bonds between earbon atoms, it is known as a saturated hydrocarbon when there is at least one double or triple bond between two carbon atoms anywhere in the molecule, it is an unsaturated hydrocarbon. When determining the saturation or unsaturation of a hydrocarbon, only the carbon-to-... 

In an unsaturated hydrocarbon, at least one of the carbon-carbon bonds in the molecule is a multiple bond. As a result, there are fewer hydrogen atoms in an unsaturated hydrocarbon than in a saturated one with the same number of carbons. We will consider two types of unsaturated hydrocarbons—... 

Compounds that contain only hydrogen and carbon are called hydrocarbons. The hydrocarbons that have only single bonds all have similar chemistry and they are called, as a family, the saturated hydrocarbons. If there are carbon-carbon double bonds, the reactivity is much enhanced. Hence hydrocarbons containing one or more double bonds are named as a distinct family, unsaturated hydrocarbons. Both saturated and unsaturated hydrocarbons can occur in chain-like structures or in cyclic structures. Each of these families will be considered. 

Unsaturated compounds are those organic compounds in which less than four other atoms are attached to one or more of the carbon atoms. Ethylene, C2H4, is an unsaturated compound. Because ethylene involves only carbon and hydrogen, it is an unsaturated hydrocarbon. Propylene, the next more complicated unsaturated hydrocarbon, has the molecular formula C3H6. 

In several papers dealing with catalytic reactions involving hydrogen and unsaturated hydrocarbons the observed self-poisoning of nickel or its alloys has been quite properly attributed to the presence of carbonaceous... 

The Mechanism of the Hydrogenation of Unsaturated Hydrocarbons on Transition Metal Catalysts G. C. Bond and P. B. Wells... 

The influence of electronegative additives on the CO hydrogenation reaction corresponds mainly to a reduction in the overall catalyst activity.131 This is shown for example in Fig. 2.42 which compares the steady-state methanation activities of Ni, Co, Fe and Ru catalysts relative to their fresh, unpoisoned activities as a function of gas phase H2S concentration. The distribution of the reaction products is also affected, leading to an increase in the relative amount of higher unsaturated hydrocarbons at the expense of methane formation.6 Model kinetic studies of the effect of sulfur on the methanation reaction on Ni(lOO)132,135 and Ru(OOl)133,134 at near atmospheric pressure attribute this behavior to the inhibition effect of sulfur to the dissociative adsorption rate of hydrogen but also to the drastic decrease in the... 

A saturated hydrocarbon is an aliphatic hydrocarbon with no multiple carbon-carbon bonds an unsaturated hydrocarbon has one or more double or triple carbon-carbon bonds. More hydrogen atoms can be added to compounds in which there are multiple bonds, but compounds with only single bonds are saturated with hydrogen. Compound (3) is saturated compounds (4) and (5) are unsaturated. 

NMHC. A large number of hydrocarbons are present in petroleum deposits, and their release during refining or use of fuels and solvents, or during the combustion of fuels, results in the presence of more than a hundred different hydrocarbons in polluted air (43,44). These unnatural hydrocarbons join the natural terpenes such as isoprene and the pinenes in their reactions with tropospheric hydroxyl radical. In saturated hydrocarbons (containing all single carbon-carbon bonds) abstraction of a hydrogen (e,g, R4) is the sole tropospheric reaction, but in unsaturated hydrocarbons HO-addition to a carbon-carbon double bond is usually the dominant reaction pathway. 

Nickel metal successfully catalyzes the hydrogenation of double bonds in unsaturated hydrocarbons such as propylene and butene. Can this metal also catalyze the dehydrogenation of alkanes such as propane and butane ... 

Ozonoiysis is a reaction used with unsaturated hydrocarbons when preparing aldehydes and ketones, by reducing intermediate ozonide or acids by oxidation. The reducing agents used include hydrogen in the presence of palladium, and zinc in acid medium. 

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